1. Field of the Invention
The present invention relates to a method of providing sub-code data of an optical disc drive, and more particularly, to a method of providing sub-code data of an optical disc drive to a host computer when the optical disc drive performs a reproduction mode.
2. Description of the Related Art
In general, a disc stores additional information other than data recorded in respective blocks on the disc. Information on the position of the recorded data among the additional information is sub-code data. For example, in the case of an audio disc, information, which is provided to a user so that the user can know which melody a currently reproduced audio signal is and what portion of the melody is currently being reproduced, is the sub-code data.
The sub-code data is recorded in the lead in (lead_in) region, the lead out (lead_out) region, and the data region (or the user region) of a disc. The sub-code data recorded in the lead in region is the table of contents (TOC) data including start time information on all the data recorded on the disc. The sub-code data for allowing the user to know the end position of the disc is stored in the lead out region.
The sub-code data for allowing the user to know the position of an actual reproduced block and a proceeding state, that is, information recorded on the optical disc, is stored in the data region. For example, a relative address for allowing the user to know the reproduction time (or the proceeding time) of a corresponding melody with respect to data recorded in a sector, and an absolute address for allowing the user to know a time, for which corresponding data is reproduced, (or a proceeding accumulating time) among the reproduction time of the entire disc, are stored in the data region. Therefore, the user can know the proceeding state of the currently reproduced data through the sub-code data recorded in a data region.
FIG. 1 is a block diagram of a general function of an optical disc drive for an audio disc, which is connected to a host computer. A loaded disc is driven according to the command transmitted from the host computer. FIG. 2 is a flowchart of the operation of a method of the optical disc drive shown in FIG. 1 providing the sub-code data to the host computer in the reproduction mode.
Referring to FIGS. 1 and 2, a conventional method of providing the sub-code data of the optical disc drive to the host computer will now be described.
First, when a command for requesting reproduction is transmitted from a host computer 109 through a decoder 105 in step 201, a micro computer 107 controls a servo driver 112 and a spindle motor driver 114 through a digital signal processor (DSP) 104 to perform the reproduction mode in step 203.
In step 205, the micro computer 107 controls the DSP 104 to convert a reproduction signal, read by a pick up 102 from a disc 101 and transmitted to the DSP 104 through an RF amplifier 103, into a digital signal, and then to transmit the converted reproduction signal to a buffer 106 through the decoder 105. When the converted reproduction signal, stored in the buffer 106 through the decoder 105, is applied to the DSP 104, the microcomputer 107 controls the DSP 104 so that the converted reproduction signal is transmitted to an audio signal processor 108. The reason why the buffer 106 is used is that the speed at which data on the disc is read by the pick-up 102 is higher than the speed of the signal reproduced through the audio signal processor 108.
When the reproduction mode is performed, the micro computer 107 continuously checks the state of the buffer 106. As a result of the check, when the state of the buffer 106 is determined to be full, the micro computer 107 requests the DSP 104 to set a temporary pause mode, as shown in step 209. Accordingly, the DSP 104 controls the servo driver 112 to allow the pick-up 102 to perform an operation according to the temporary pause mode.
At this time, when the sub-code data is requested by the host computer 109 (step 211), the micro computer 107 requests the DSP 104 to detect the position of the reproduced data from the disc (step 212). The DSP 104 then provides the subcode data based on the RF signal transmitted from the RF amplifier 103 to the host computer 109 through the decoder 105 in step 215.
In step 217, the micro computer 107 checks whether reproduction termination is requested. As a result of the check, when the reproduction termination is not requested, the process returns to step 207 and the above processes are repeated. When the reproduction termination is requested, the microcomputer 107 terminates the reproduction mode.
However, when the pick up 102 is set to be in a temporary pause mode as mentioned above, the pick up 102 repeatedly jumps a track of a certain position within a temporary pause region on the basis of the track, in which the buffer 106 is set to be in a full state. This means that the disc 101 continuously rotates by a spindle motor 115 even in the temporary pause mode.
Therefore, when the sub-code data is requested from the host computer 109 in a state where the pick up 102 is set to be in the temporary pause mode, the sub-code data including the error of the track according to the temporary pause region is provided on the basis of the track of the data finally stored in the buffer 106. Accordingly, the correct sub-code data is not provided to the host computer 109. This can lead to unnatural reproduction being performed during reproductions such as automatic reproduction or game CD reproduction.